Color developer sheet for pressure sensitive recording paper

ABSTRACT

A COLOR DEVELOPER SHEET FOR PRESSURE SENSITIVE RECORDING PAPER COMPRISING A COLOR DEVELOPER LAYER CONTAINING A METALLIC COMPOUND OF A PHENOL COMPOUND, SAID PHENOL COMPOUND PKA BELOW 8.

United States Patent 3,334,929 COLOR DEVELOPER SHEET FOR PRESSUREEENSITIIVE RECORDING PAPER Takao Hayashi and Hajime Kato, Fujinomiya,and Sadao Ishige, Minami Ashigara, Japan, assignors to Fuji Photo Film(10., Ltd., Kanagawa, Japan N0 Drawing. Filed Dec. 16, 1971, Ser. No.208,894

Claims priority, application Japan, Dec. 26, 1970,

45 118,97 8 Int. Cl. B41m /22 U.S. Cl. 117-362 7 Claims ABSTRACT OF THEDISCLOSURE A color developer sheet for pressure sensitive recordingpaper comprising a color developer layer containing a metallic compoundof a phenol compound, said phenol compound pKa below 8.

BACKGROUND OF THE INVENTION Field of the Invention The present inventionrelates to a color developer sheet for pressure sensitive recordingpaper. More particularly, the present invention relates to a colordeveloper sheet for pressure sensitive recording paper using a metallicphenol compound which is a metal phenolate and which has not hithertobeen used as a color developer.

Description of the Prior Art Pressure sensitive recording papers utilizethe reaction of a colorless organic compound (hereinafter referred to asa color former) and a color developing material (hereinafter referred toas a color developer) capable of reacting with the above color former toform a colored product.

Usually pressure sensitive recording papers are composed of a sheet(color former sheet) having coated thereon microcapsules containing asolution of color former in an organic solvent and a sheet (colordeveloper sheet) having coated thereon a color developer with a binder,and may include a sheet having coated on one side a color developer andon the other side the microcapsules (such assemblies are hereinafterreferred to as pressure sensitive duplicating papers). Sheets are alsoformed having microcapsules and the color developer on the same side ofthe support (called single recording paper).

As color formers, malchite green lactone, benzoyl leucomethylene blue,crystal violet lactone, Rhodamin B lactam, 3-dialkylamino-7-dialkylaminofluoranes, 3-alkyl- 2,2-spiro bi(benzo f Chromene), etc. have been used.

As color developers, there have been used clays such as acidic clay,attapulgite, kaoline, geolite, pyrophilite, bentonite, haloycite, andphenol compounds such as pcresol, p-phenyl phenol, pentachlorophenol,pentamethylphenol, p,p'-biphenol, 5,5 diethyl-o,o-biphenol, 2,2-rnethylene bis (4-chlorophenol), 4,4-thiodiphenol, etc. as described inthe specification of Japanese Pat. 465,300. However, clays such asacidic clay and active clay are usually employed.

Conventional color developers using clays tend to adsorb materials fromthe air at the active point of the clay when allowed to stand in air,and remarkably lower in color developing ability. Though color developerclays have a higher color developing ability than that of other colordevelopers (p-cresol, p-phenylphenol and the like), the color developingability thereof is lowered when it is exposed to sun-light. In addition,the colored body on the color developer sheet has the defect that whenwet with water the color disappears or is lowered in concentration.

The color developer sheets using the above described phenol compoundscannot be used as a practical matter since although they have good waterproofness as a colored body on the sheet, they are low in colordeveloping ability, which is most important and also is poor in lightresistance of the colored body 011 the sheet.

SUMMARY OF THE INVENTION The present inventors have found that by usinga metallic phenol compound as a color developer a color developer sheetwhich is high in color developing ability, good in water resistance as acolored body and exhibits less lowering of activity can be obtained. Theobject of the present invention is thus to provide a color developersheet for pressure sensitive duplicating papers which meets the abovecriteria and does not have the substantial defects of the prior artcolor developer.

DETAILED DESCRIPTION OF THE INVENTION The metallic compound of phenolused in the present invention is obtained by reacting an alkali metalsalt of a phenol compound and a water soluble metallic salt in asolvent. In this case, the alkali metal salt of the phenol compound andthe water soluble metallic salt can be used at any ratio, although thewater soluble metallic salt is preferably used in an amount greater than1 gram equivalent per gram equivalent of the alkali metal salt of thephenolic compound.

The reaction can be attained by adding an aqueous solution of awater-soluble metal compound to an aqueous solution of alkali metal saltof phenol compound. The addition of the compounds may be carried out inreverse order, of course. 7

The metal compound of phenol is immediately produced. In the reaction,reaction condition such as temperature or pressure are of no importance,and the reaction proceeds at normal condition.

Various methods are known for synthesizing the alkaline salts of suchphenol compound or aqueous solutions thereof. For example, one method ofobtaining an alkali salt of phenol or its aqueous solution is byreacting the base phenol compound with an alkali metal, a hydroxide orcarbonate of the alkali metal in an amount of one gram equivalent ormore of the above hydroxide or carbonate per one gram mole of the alkalisalt of phenol. Other methods may, of course, be used, but the abovemethod is very simple.

As the phenol compound used to form the metal compound of a phenolcompound in the present invention phenols having pKa of below 8 such as2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol,pnitrophenol, p-methylsulfonyl-phenol, methylsulfonyl phenol, 4-phenylsulfonyl phenol, 4-cyanophenol, 2,4-dicyanophenol, 4-cyano-Z-chlorophenol, 2,4-dichloro-4-cyanophenol, tetrachloro-bis phenolA, 4,4-dihydroxy-3,3'-dichlorodiphenylsulfone, 4,4 dihydroxy 3,3',5,5'-tetrachlorodiphenyl sulfone, etc. are effective.

The present inventors have tried to synthesize a metallic phenolcompound from a phenol compound above 8 in pKa. However, a phenolcompound of above 8 in pKa does not make a metallic compound as shown bythe infra-red absorption curves and the color developing ability of theproduct. These are not different from those of the phenol monomercompound itself. Herein, pKa=log (acidity constant).

As water soluble metallic salts used in the present ine as chromium,molybdenum, etc., Group VIIb metals such as manganese, etc., and GroupVIII metals such as cobalt, nickel, etc.

Among these, the water soluble salts of zinc, nickel, manganese, copper,magnesium, calcium, are particularly preferred. As representative watersoluble metallic salts inorganic salts such as chlorides, sulfates,nitrates, etc. and organic salts such as acetates, oxalates, etc. of theabove described metals can be employed.

To manufacture the color developer sheet of the present invention, atleast one metallic phenol compound produced by the reaction of the abovedescribed alkaline phenol salt and the above described water solublemetallic salt (either in the form of a reaction mixture or, preferably,after it has been separated and purified) is coated with a binder onto asupport such as paper, synthetic paper etc., in an amount of above 0.1g./m. desirably 0.2 to 5 g./m. The upper limit of the coating amount isprimarily determined by reasons of economy and coating workability.

The binder is not necessarily used (that is, the metallic phenolcompound is dissolved for use as an ink), but if it is used, the amountthereof is preferably from about 5 to about 50 parts by weight,preferably parts by weight, based on 100 parts by weight of the metallicphenol compound. Those skilled in the art will appreciate these figurescan vary.

As the medium for applying the color developer of the present invention,water or various organic solvents can be used alone or in any mixingratio. The organic solvents used include methanol, ethanol, butanol,acetone, n-butyl acetate, benzene, toluene, methylene chloride, etc.

As the binder, cellulose derivatives such as nitrocellulose, natural orsynthetic polymers such as vinyl acetate, vinyl chloride, polyamide,polyacrylic acid, styrenebutadiene copolymer, casein, polyvinyl alcohol,gelatine, gum arabic, etc., latexes such as styrene-butadiene latex,butadienemethylmethacrylate latex, etc. are primarily employed.Essentially any polymeric binder used in the prior art can be used forthe same purpose in the present invention.

The color developer sheet using the color developer of the presentinvention may be used in combination with a color former sheet and theremay be arranged thereon a rnicrocapsule layer containing a color former.The color developer of the present invention may also be mixed with themicrocapsules and coated onto a support, for example, a paper.Furthermore, as another method of use, a color developer ink containingthe above compound can be printed onto a paper by a printing process.

The color developer sheet using the color developer of the presentinvention has the following excellent effects in comparison with theconventional color developer sheet using clays such as acidic clay, etc.

Clay paper is remarkably lowered in color developing ability when it isallowed to stand in a room and the color developer sheet of the presentinvention is greatly improved at this point.

Further, although almost all colored material on a conventional claypaper disappears or is lowered in color concentration upon wetting withwater, the colored material on the color developer sheet of the presentinvention is not lowered in concentration even if wet with water. Inaddition, for the case of manufacturing a color developer sheetaccording to the present invention, sufficient color developing abilityand other properties necessary for a color developer sheet for pressuresensitive recording paper are satisfied with a smaller amount of coatingthan in conventional clay paper. That is, conventional clay paperrequires a coating amount of 7 to 10 g./m. while the color developer ofthe present invention is suffi cient at a coating amount of 0.2-5 g./m.Thus, a small amount of coating is sufiicient and the physicalproperties of the coating liquid can be freely varied in a mannerimpossible with clay coatings.

Furthermore, when coating the color developer onto a paper previouslycoated with a natural or synthetic high molecular weight substance or arepellent, the same color developing ability can be obtained withsmaller amount of coating.

Finally a color developer sheet using a metallic phenol compound isremarkably higher in color developing ability and in light fastness ofthe colored material formed up on the color developer sheet, as comparedto a color developer sheet using a phenol compound per se as a colordeveloper.

The present invention will be illustrated in great detail by thefollowing Examples which, of course, are not to limit the presentinvention, where all parts are by weight unless otherwise indicated.

The effect of the color developer sheet of the present invention wasconfirmed with the following color former sheet. The microcapsulescontaining color former were manufactured according to U.S. Pat.2,800,457, using the following procedure.

10 parts of acid treated pig skin gelatin and 10 parts of gum arabicwere dissolved in 40 parts of water at 40 C. and 02 part of Turkey redoil was added thereto as an emulsifier, whereafter 40 parts of colorformer oil were emulsified and dispersed therein. The color former oilwas 2% crystal violet lactone dissolved in an oil consisting of 4 partsof chlorinated diphenol and 1 part of kerosene. Emulsification wasstopped when the oil droplet size was an average of 5 microns. 900 partsof water at 40 C. was added thereto and stirring was continued. At thistime care must be taken so that the liquid temperature does not fallbelow 40 C. Then 10% acetic acid was added thereto to adjust the pH ofthe liquid to 4.0 to 4.2, resulting in coacervation. The stirring wascontinued further and, after 20 minutes, the system was cooled with iceto gel the coacervate film deposited around the oil droplets. When theliquid temperature reached 20 C., 7 parts of 37% formaldehyde were addedthereto and, at 10 C., a 15% aqueous solution of caustic soda was addedto adjust the pH to 9. The addition of caustic soda should be carriedout at 10 C. to obtain the best results. The liquid temperature was thenraised to 50 C. with stirring for 20 minutes. The microcapsule, thusobtained were conditioned at 30 C. and thereafter directly coated onto a40 g./m. paper to a 6 g./m. solids content, and dried. And in case ofother color former the recording paper was manufactured in the samemanner as described above.

Example 1 0.01 g. equivalent of caustic soda was dissolved in 30 ml. ofwarm water and 0.01 g. equivalent of phenol compound (see Table 1) wasdissolved therein. 0.01 g. equivalent of the below described watersoluble metallic salt dissolved in 10 ml. of warm water was then addedto this solution with stirring.

Crystals immediately precipitated out. The crystals were filtered andwashed with water several times and dried.

The product obtained by the above method Was dissolved or dispersed in30 ml. of ethanol to obtain a coating liquid. This coating liquid wascoated onto a 40 g./m. paper by a glass tube at a solid content of 0.5g./m. and dried to obtain a color developer sheet.

Comparative Example 1 3 g. of phenol compound per se were dissolved in30 ml. of ethanol and the resulting ethanol solution was coated on a 40g./rn. paper by a glass tube at solids content of 0.5 g./m. and dried toobtain a color developer sheet.

Example 2 0.01 g. equivalent of caustic soda was dissolved in 30 ml. ofwarm water and 0.01 g. equivalent of phenol compound was dissolvedtherein. 0.01 g. equivalent of the below described water solublemetallic salt dissolved in 10 ml. of warm water was added to thissolution with stirring.

Furthermore, 0.5 g. of the below described binder dissolved in ml. ofwarm water was added thereto to obtain a coating liquid. This liquid wascoated onto a paper at a solids content of 0.5 g./m. and dried to obtaina color developer sheet.

6 ability for crystal violet lactone and 3-dibenzylamino-7- diethylaminofluorane color formers and, in addition, in the light fastness ofthe colored body in comparison with using only a phenol compound as acolor developer. The colored body produced in accordance with thepresent invention was not lowered in color concentration even if Testresults wetted with water.

(1) The color developer sheet of Example 1 and Com- 'For other colorformers the same results were obparative Example 1 were color developedby stocking tained. In the color developer sheet of the present inpapercoated with microcapsules containing crystal violet 1O vention inExample 2, as shown in Table 2, the color lactone thereon (heretoforedescribed) and applying a developing ability for crystal violet lactoneand 3-di- 600 leg/cm. load thereto. After standing at a dark placebenzylamino-7-diethylamino-fiuorane color formers was for 1 hour, thespectral absorption curve in the 700 to high, and the light fastness ofthe colored body was high. 400 m wave length region was measured and thecon- In addition, the colored body was not lowered in color centrationat the maximum absorption (wave length 610 concentration even if wettedwith water.

TABLE 2 Light fast- Color con- Light fastness ness of centration of ofcolored colored 3-dlibcnzy1- body 01'3- body of amino-7- dibenzylamino-Color concrystal diethyl- 7-diethylcentration of violet amino aminoWater soluble crystal violet lactone Iluorane fiuorane Phenol compoundmetallic salt Binder lactone (D1) (percent) (D 1) (Percent) Example 2.Pentachlorophenol Zinc sulfate Polyvinyl alcohol. 0.897 60 0.648 97 Dodo Magnesium sulfate ..do 0. 953 73 0.651 94 Do do Tin chloride Gumarabic... 0.498 55 0.436 83 Do. 2,4,6-trichlorophenol. Nickel sulfateSodium alginate 0.542 47 0.477 85 Do 2,4-dicyanophenol Manganesechloride do 0.625 52 0.542 81 Do 4-pheny1sulfonylphenol Copper sulfateGum arabic 0.551 50 0. 524 76 m was taken as the fresh concentration.After irradia- Example 3 F g i i gg gg i z g i 355g: 1 5 33333 parts ofethyl cellulose were homogeneously disve n at th nfaxim absor fion Wavelen th solved in a mixed solution of 15 parts of dibutyl phthalate, gfafg m 10 e L p g 100 parts of ethylacetate, 90 parts of butyl acetate, 80

parts of isopropyl alcohol and 60 parts of butanol, and b g fi g ig l ggi fg fi value defined 120 parts of the zinc salt of pentachlorphenolwas mixed Y e g q S 3;) into this solution and completely dissolved ordispersed Light fastness value by means of a ball mill to obtain a whitesuspension of color developing ink. The ink was diluted with a mixed tmxim m losor tion Concentmmon i n p S nu ht solvent of ethyl acetate andethanol (1:1) so that the 1 a 1 10 W1 u 100 40 viscosity was about 0.7poise, and printing was conducted Flesh concentration at maximumabsorption by the flexo printing method to give a 3 2 dried To measurethe spectral absorption curve a Beckmann film. spectroscope Type DB(manufactured by Toshiba Co.) Thus obtained developer sheet wascontacted with a was d color former sheet same as in the former Examplesto (2) A color developer sheet coated with a microcapbtam the similarresults. sule containing 3 dibenzylamino-7-diethylaminofluorane What isclaimed is: was color developed in the same manner and, after stand- 1.A pressure-sens1t1ve recording sheet which comprises ing in a dark placefor 1 hour, the spectral absorption 21 color developer layer capable ofreacting with a color curve in the 700 to 400 m wave length region wasformer t0 form acolof Productcomprising! measured, and the concentrationat the maximum aba support sheet having coated thereon the colordesorption (wave length 600 mg) was taken as fresh conveloper layercontaining a metal phenolate, said centration. Further, afterirradiation with sun light for 2 ph nolate having a pKa value of below 8and being hours, the spectral absorption curve of the colored body Capal f reacting with the color former to form was measured to obtain theconcentration at the maxi- Said Color product. mum absorption (Wavelength 530 me). The light fastsaid metallic member of said metalphenolate being a nesswas obtained in the same manner as in(l). metalbelonglng to a member t d fr m th TABLE 1 Light fastness of Colorconcencolored body of Color con- Light fastness tration of 3-3-dibenzylcentration of colored body dibenzylamiamino-7-diof crystal ofcrystal no-7-diethylcthylamino- Water soluble violet lacviolet laetoncaminofiuorane fluorane Phenol compound metallic salt o i) (P i)(percent) Example 1 Pentachlorophenol. Zinc chloride 0.889 66 0.650 102Do 2 pentachloropheno 0.907 61 0.652 99 Do do 0. 739 48 c. 691 86 Do doMagnesium sl11fate- 0. 961 0.662

Do .do Manganese chloride. 0.770 69 0. 663 108 Do do Nickel sulfate0.873 75 0.647 109 Comparative Example 1. .do 0. 164 Disappearance 0.155 Disappearance Example 1 2,4,6-trichlorophen0L. 0. 530 42 0. 453 82Comparative Example 1 o 0.061 Disappearance 0.056 Disappearance Example1 2,4-dichlorophenol 0.516 45 0.435 85 Comparative Example 1- o 0.052Disappearance 0.048 Disappearance Example 1 2,4-dichloro-4-cyanophenolManganese suliate 0.643 54 0.566 9 Comparative Example 1 ..do 0.Dlsappearance 0.119 Disappearance The color developer sheet of thepresent invention was thus formed to be remarkably higher in colordeveloping group consisting of Group Ib, Group Ila, Group IIb, GroupIIIa, Group IVa, Group VIb, Group VIII) and Group VIII of the PeriodicTable.

2. A pressure-sensitive recording sheet as claimed in Claim 1 whereinsaid metal phenolate is obtained by reacting an alkali metal salt of aphenol compound and a water soluble metallic salt.

3. A pressure-sensitive sheet as claimed in Claim 2 where the watersoluble metallic salt is used in an amount greater than 1 gramequivalent per gram equivalent of the alkali metal salt of the phenolcompound.

4. A pressure-sensitive recording sheet as claimed in Claim 1 whereinthe phenol compound utilized to provide said metal phenolate is ahalophenol, a nitrophenol, an alkylsulfonyl phenol, an arylsulfonylphenol, a cyanophenol, a halocyano phenol, a bisphenol, ahydroxyhalophenylsulfone.

5. The pressure-sensitive recording sheet of Claim 1, wherein said metalis a member selected from the group consisting of zinc, nickel,manganese, cobalt, magnesium and calcium.

6. The pressure-sensitive recording sheet of Claim 1,

wherein said color former is present in a color former sheet differentfrom said support sheet having coated thereon said color developerlayer.

7. The pressure-sensitive recording sheet of Claim 1, wherein said colorformer is present in said color developer layer.

References Cited UNITED STATES PATENTS 3,592,677 7/1971 Tsuboi et a1.1l7-36.8 3,079,270 2/1963 Cortez 117-154 2,680,097 6/1954 Stewart260-621 F 2,579,329 12/1951 Martin 260621 P WILLIAM D. MARTIN, PrimaryExaminer W. R. TRENOR, Assistant Examiner US. Cl. X.R.

